Electric contact governor



Dec. 18, 1934. w, A. ANDERSON ELECTRIC CONTACT GOVERNOR Filed Dec. 25, 1932 Patented Dec. 18, 1.934

UNITED STATES PATENT OFFICE mesne assignments,

to Underwood Elliott Fisher Company, New York, N. Y., a corporation of Delaware Application December 23, 1932, Serial No. 648,544

ll Claim.

Satisfactory operation of a motor-driven computing machine requires that the machine be driven at a iixed predetermined speed. Several factors may tend to cause variations in speed,

as, for example, fluctuations in line voltage, variations in the load imposed upon the motor in the operation of the machine, and variations in friction in the machine bearings. Attempts have been made, with more or less success, to control the speed of the motor by employing a centrifugal governor to operate a switch included in the motor circuit, but such so-called contact governors have possessed undesirable characteristics such as noisiness, excessive wear of the contact points, relatively great cost, or lack of compactness.

` The object of the present invention is to produce a centrifugal governor which shall be thoroughly reliable and efficient in operation, free from noise, compact, comparatively simple, and relatively inexpensive.

In the accompanying drawing Figure 1 is a side elevation of an electric drive unit for an adding machine such as is disclosed in application Ser. No. 399,612, led October 14, 1929, by Oscar J. Sundstrand.

Fig. 2 is an end elevation of the contact governor, the view being taken in the plane of line 2-2 of Fig. 1.

) Figs. 3 and 4 are sections on line 3-3 of Fig. 2, Fig. 3 showing the parts at rest, and Fig. 4 repesenting the governors operation.

In Fig. 1, M is the motor, M' is the armature shaft, R is the speed-reduction gearing between the armature shaft and the adding or other machine to be driven, C is the case or housing that encloses the gearing R, and G is the governor. The latter comprises a disk 1 rigidly secured to the end of the armature shaft. A

vspring arm 2 extends radially of the disk, the end 3 of said arm being rigidly attached to the disk 1 by means of screws 4. The tension of the spring arm 2 normally holds it flat against the outer face of the disk. The major portion of the length of the arm 2 is rendered rigid by securing thereto a sti'ening plate 5. On the free end of the arm 2 is fastened a weight 6 which projects through a notch 7 in the disk 1, and which is therefore normally out of the plane of rotation of the end 3 of the arm 2.

When the disk l isv rapidly rotated, centrifugal force causes the weight 6 to assume a position wherein the center of gravity of the arm 2 and the parts carried thereby is in or near the plane of rotation of the end 3, thus causing the (Cl. 20o- 80) arm 2 to flex adjacent to the end 3. Such movement of the arm 2 is utilized to operate a switch which is connected into the circuit that supplies current to the motor M. The switch comprises a rigid contact nger 8 secured to the gear housing C by means of screw studs 9, but insulated therefrom by means of a bushing 10. The finger 8 is provided with -a contact 11 of any suitable conducting material. The switch further comprises a flexible contact finger 12 supported on the screw studs 9 but insulated therefrom and from the finger 8 by means of the bushing 10 and a spacer 13. The finger 12 carries a contact 14 arranged to coact with the contact 1l. The fingers 8 and 12 extend radially of the shaft M', and the contacts 11 and 14 are located at one side of the axis of said shaft. The contact fingers 8 and 12 are normally substantially parallel, the rigid finger 8 being located between the spring arm 2 and the spring finger l2.

A projection 15 of insulating material is rigidly secured to the arm 2 and is located on said arm in the projected axis of the shaft M. The contact finger 8 has an opening 16 to accommodate the projection 15. On the contact finger 12 is a projection in the nature of a screw 17 having a screw-thread engagement with a bushing 18 carried by said finger. 19 is a lock nut on the screw 17 to hold the latter in adjusted position. The inner end of the screw 17 is located in vposition to be engaged by the projection 15 when the arm 2 is flexed outwardly by centrifugal force.

The contact fingers 8 and 12 are connected into the circuit that supplies electric current to the motor M by means of Wires 20 and 2l, respectively.

In use, the speed at which the motor should operate is determined by so adjusting the screw 17 that the flow of current across the contacts l1 and v14 will be interrupted or reduced through separation of the contacts as the contact arm 12 is flexed by the pressure of the projection 15 against said screw when the motor tends to exceed such predetermined speed, due to increased line voltage, fluctuations in driven load or other causes.

It will be noted that the contacts 11 and 14 do not rotate relatively to each other, that there is no rubbing contact anywhere in the governor except that between the projections 15 and 17, and that the contact between said projections is approximately at a point and is practically in the axis of rotation of the part 15. Hence there is so little wear or destruction of parts that the governor will operate eiliciently for a long time with- Cil out "adjustment, Moreover the substantial elimi nation of the rubbing contact which was common in prior types of motor governors also conduces to noiselessness. Compact-.ness and simplicity are further important characteristics of the present construction, it being noted in this connection that Figs. 2, 3 and 4 are much enlarged, as compared with the commercial product;

I claim as my invention:

A governor for operating a switch included in ay motor circuit, said governor comprising in connection a motor-driven rotary member, a spring arm secured at one end to said member and extending radially of said member, a weight attached to the other end of said arm and located at one side of said arm so as to be movable by centrifugal force, to ex the arm away from said member, a rigid contact iinger and a spring contact iinger in generally parallel arrangement ad jacent to the spring arm, said rigid contact nger being located between the spring arm. and the contacts being normally in engagement with each other, an adjusting screw on the spring contact nger located in approximately the axis of said rotary member, the manipulative endy of said screw being positioned on the side of said last mentioned linger away from said rigid contact nger to facilitate adjustment. and a projection on the spring arm ed in the flexing of said arm to make substantially point 'contact with the end of said screw in substantially the axis of said rotary member to ilex the spring contact arm to separate the contacts and thus maintain constant v a WALTER A. ANDERSON. 

